Chemical base for engine coolant / antifreeze with improved thermal stability properties

ABSTRACT

The present invention relates to a antifreeze/coolant composition for use in internal combustion engines which comprises: an anti freeze/coolant for diesel engines which comprises: 1,3 propanediol 97-98% by volume, 95 to 97 percent; nitrite, 0.50 to 1.5%; nitrate, 0.30 to 1.5%; borate, 0.25 to 1.25%; mercaptobenzothiazole, 0.25 to 1.0%; tolyltriazole, 0.30 to 1.1%; benzyltriazole, 0.00 to 1.0%; silicate, 0.25 to 3.0%; antifoam, 0.05 to 0.3%; silicate stabilizer, 0.10 to 1.9%; and dye, 0.00 to 0.02% In another embodiment, the present invention relates to a different antifreeze/coolant composition for use in internal combustion engines which comprises: an anti freeze/coolant for diesel engines which comprises: 1,3 propanediol 97-98% by volume, 95 to 97 percent; nitrite, 0.50 to 1.50%; nitrate, 0.30 to 1.50%; phosphate, 0.50 to 1.60%; mercaptobenzothiazole, 0.25 to 1.00%; tolyltriazole, 0.30 to 1.10%; benzyltriazole, 0.00 to 1.00%; silicate, 0.25 to 3.00%; molybdate, 0.50 to 1.30%; antifoam, 0.05 to 0.10%, and dye 0.00 to 0.02%. In another embodiment, PDO is 93 to 95% by weight, 2-ethylhexanoic acid is 4.0 to 6.0%, sebacic acid is 0 to 1.5%, sodium tolyltriazole is 0.3 to 1.1%, antifoam is 0.05 to 0.3% and dye is 0 to 0.02%. In the fourth embodiment, PDO is 93 to 95% by weight, sodium nitrite is 0.5 to 1.5%, 2-ethylhexanoic acid is 4.0 to 6.0%, sebacic acid is 0 to 1.5%, sodium tolyltriazole is 0.3 to 1.1%, antifoam is 0.05 to 0.3% and dye is 0 to 0.02%.

CROSS REFERENCE TO PRIOR APPLICATIONS

[0001] This application claims priority to provisional applicationsSerial Nos. 60/261,764 filed Jan. 16, 2001, 60/267,053 filed Feb. 6,2001, and 60/268,642 filed Feb. 14, 2001.

FIELD OF THE INVENTION

[0002] This invention relates to antifreeze/coolants which can be usedfor internal combustion engines and fuel cells. More particularly, thisinvention relates to such compositions which contain mostly 1,3-propanediol as the primary antifreeze/coolant and can also contain otheringredients as required for the particular use.

BACKGROUND OF THE INVENTION

[0003] Increasingly challenging international engine emissionsreductions have resulted in some advances in engine emissionstechnologies that may motivate a change from the customary ethyleneglycol and/or propylene glycol bases that have been the mainstay ofengine antifreeze formulations for almost a century. The new engines'components, especially exhaust gas recirculation (EGR) devices, generatemuch greater thermal stress on the engine coolant. The oxidation ofethylene glycol and propylene glycol may be accelerated dramatically,resulting in coolant unsuitable for continued use in as little as a fewmonths. The industry has been working towards extended engine coolantservice intervals, with some recommendations for service extended to aslong as five years. It follows, therefore, that a requirement forcoolant change at four to six month intervals (due to acceleratedoxidation & aging) would be unacceptable to vehicle owners. There areother technologies than EGR for lowering exhaust emissions that havesimilar problems. The present invention is also advantageous for thoseother emissions lowering technologies.

[0004] Coolants are generally evaluated and judged by subjecting them toa series of physical properties and performance tests and then comparingthe data to the specifications published by ASTM. This invention relatesto a new coolant base chemistry, known here as 1,3-propanediol by Shell,which is tested according to the ASTM D3306 Light and Medium Duty(Automotive) and D6210/6211 “Fully Formulated Engine Coolant” physicaland performance testing protocols. These protocols qualify an enginecoolant for use in virtually any engine cooling system, gasoline(petrol), diesel, and natural gas; engineered with or without wet sleevecylinder liners.

[0005] Diesel engine original equipment manufacturers (OEMs) arevigorously working to prepare low-emissions diesel-fueled engines thatwill meet the emissions requirements of North American and Europeanregulatory agencies in the first decade of the twenty-first century.Extensive investments and research into various possible designimprovements have generated some effective technologies such as exhaustgas recirculation devices (EGRs), referred to above. EGR devices, as thename implies, pass part of the exhaust gas back to the combustionchamber to increase the combustion efficiency of the engine, resultingin the lowering of target emissions. Exhaust gasses, especially thoseproduced by a diesel engine, are much hotter than regular intake air.The EGR gasses, therefore, must be cooled by the existing engine coolantsystem before they reach the combustion chamber.

[0006] Coolant blended from ethylene glycol (EG) for heavy-duty dieselapplications in prototype EGR-equipped engines sometimes experiencesdiscoloration and rapid oxidation. Oxidation reactions include nitrite(NO₂) to nitrate (NO₃) and ethylene glycol (HO—CH₂—CH₂—OH) to formicacid (CH₃—OOH) and glycolic acid (HO—CH₂—CH₂—OOH). In the presence ofthe EGR, EG degradation is greatly accelerated. This degradation resultsin an increase in corrosive properties that attack engine components andcause premature failure. Although propylene glycol (PG) coolants havenot been tested with EGR devices, PG is generally considered even lessthermally stable than EG.

[0007] The diesel engine emissions requirements for the model year 2002heavy-duty diesel engines have resulted in experimentation with exhaustgas recirculation devices. Diesels with EGRs have been developed andtested in various environments. In some tests the engine coolant turnedblack and produced a strong, unpleasant odor. Chemical analysis of theused coolant revealed very high concentrations of formates andglycolates. In addition, the nitrite concentration had been prematurelydepleted by oxidation to nitrate, as was the silicate. The coolants' pHhad dropped from 10.2 to 8.3 in just a few months' service. Overall,this change results in a corrosive coolant that may attack, and causepremature failure of, cooling system components.

[0008] Ethylene glycol (1,2 ethanediol) and propylene glycol (1,2propanediol) have offered the lowest-cost chemical bases for engineantifreezes/coolants for many decades. The current ASTM specificationsfor EG based engine coolants are ASTM D3306 (automotive and light duty)and D6210 (fully formulated heavy duty). If EG and PG were found to beincapable of service in EGR-equipped diesel engines, 1,3-propanedioloffers a more stable, longer lived alternative.

SUMMARY OF THE INVENTION

[0009] The present invention relates to a antifreeze/coolant compositionfor use in internal combustion engines which comprises: an antifreeze/coolant for internal combustion engines which comprises: 1,3propanediol (PDO) 97-98% by volume, 95 to 97 percent; nitrite, 0.50 to1.5%; nitrate, 0.30 to 1.5%; borate, 0.25 to 1.25%;mercaptobenzothiazole, 0.25 to 1.0%; tolyltriazole, 0.30 to 1.1%;benzyltriazole, 0.00 to 1.0%; silicate, 0.25 to 3.0%; antifoam, 0.05 to0.3%; silicate stabilizer, 0.10 to 1.9%; and dye, 0.00 to 0.02%

[0010] In another embodiment, the present invention relates to adifferent antifreeze/coolant composition for use in internal combustionengines which comprises: an anti freeze/coolant for diesel engines whichcomprises: 1,3 propanediol 97-98% by volume, 95 to 97 percent; nitrite,0.50 to 1.50%; nitrate, 0.30 to 1.50%; phosphate, 0.50 to 1.60%;mercaptobenzothiazole, 0.25 to 1.00%; tolyltriazole, 0.30 to 1.10%;benzyltriazole, 0.00 to 1.00%; silicate, 0.25 to 3.00%; molybdate, 0.50to 1.30%; antifoam, 0.05 to 0.10%, and dye 0.00 to 0.02%.

[0011] In another embodiment, PDO is 93 to 95% by weight,2-ethylhexanoic acid is 4.0 to 6.0%, sebacic acid is 0 to 1.5%, sodiumtolyltriazole is 0.3 to 1.1%, antifoam is 0.05 to 0.3% and dye is 0 to0.02%. In a fourth embodiment, PDO is 93 to 95% by weight, sodiumnitrite is 0.5 to 1.5%, 2-ethylhexanoic acid is 4.0 to 6.0%, sebacicacid is 0 to 1.5%, sodium tolyltriazole is 0.3 to 1.1%, antifoam is 0.05to 0.3% and dye is 0 to 0.02%.

[0012] In still another embodiment, PDO is used as a coolant in fuelcell vehicles. It provides high electrical resistance, corrosionprotection without traditional corrosion inhibitors, freeze protectionto at least −44° C., improved operator safety by not conducting anintense electric field to serviceable components, and offers theoptional embodiment of dilution up to 60 percent by weight withdeionized water for improved economy.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 illustrates the aqueous solution freeze pointcharacteristics of the 1,3-propanediol and GM 6043 inhibition chemistry(EG).

[0014] FIG. 2 shows the anions present in Type ‘A’ Coolants.

[0015] FIG. 3 shows the anions present in Type ‘B’ Coolants.

DETAILED DESCRIPTION OF THE INVENTION

[0016] 1,3-propanediol, which is manufactured by Shell Chemical Company,is generally made as described in U.S. Pat. No. 5,304,691 and the artdescribed therein. This is a process for making PDO and HPA(3-hydroxypropanal, a 3-hydroxyaldehyde). In this particular patent, PDOand HPA are made by intimately contacting an oxirane (ethylene oxide,hereinafter ‘EO’), a ditertiary phosphine-modified cobalt carbonylcatalyst, a ruthenium catalyst promoter, and syngas (carbon monoxide andhydrogen) in an inert reaction solvent at hydroformylation reactionconditions. A PDO yield of up to 86-87 mole % is reported, using acatalyst comprising cobalt ligated with1,2-bis(9-phosphabicyclononyl)ethane as bidentate ligand, and eithertriruthenium(0) dodecarbonyl or bis[ruthenium tricarbonyl dichloride] ascocatalyst. Other methods of making PDO are known.

[0017] This invention is a PDO-based antifreeze/coolant compositionwhich is intended to be blended with water and used as the heat exchangemedium in the cooling systems of internal combustion engines, especiallydiesel engines. It may also be used in cooling systems of other internalcombustion engines. The PDO is the basic ingredient and it comprisesfrom 95 to 97 percent by weight of the composition. However, thecomposition must also contain an inhibitor package. There are at leastbasically four types of inhibitor packages. One which contains a boratecompound, Type A below, such as borax (sodium borate).

[0018] Another type of inhibitor, Type B below, package instead containsa phosphate, such as sodium phosphate, and also a molybdate, such assodium molybdate. Then there are the organic acid and heavy duty organicacid inhibitor packages. These are generally and specifically describedin the following tables. TABLE 1 TYPE ‘A’ Chemical Percentage 1,3Propanediol 97-98% by volume 95 to 97 percent Sodium Nitrite 0.50 to1.5% Sodium Nitrate 0.30 to 1.5% Borax 0.25 to 1.25% SodiumMercaptobenzothiazole 0.25 to 1.0% Sodium Tolyltriazole 0.30 to 1.1%Sodium Benzyltriazole 0.00 to 1.0% Sodium Silicate 0.25 to 3.0% Antifoam0.05 to 0.3% Silicate stabilizer 0.10 to 1.9% Dye 0.00 to 0.02%

[0019] TABLE 2 TYPE ‘B’ Chemical Percentage 1,3 Propanediol 97-98% byvolume 95 to 97 percent Sodium Nitrite 0.50 to 1.50% Sodium Nitrate 0.30to 1.50% Sodium Phosphate 0.50 to 1.60% Sodium Mercaptobenzothiazole0.25 to 1.00% Sodium Tolyltriazole 0.30 to 1.10% Sodium Benzyltriazole0.00 to 1.00% Sodium Silicate 0.25 to 3.00% Sodium Molybdate 0.50 to1.30% Antifoam 0.05 to 0.10% Dye 0.00 to 0.02%

[0020] Both compositions contain from 0.5 to 1.5 weight percent of anitrite, such as sodium nitrite, and from 0.3 to 1.5 weight percent of anitrate, such as sodium nitrate. The nitrate ion provides protectionfrom pitting and crevice corrosion.

[0021] Both compositions must contain from 0.25 to 3.0 weight percent ofa silicate, such as sodium silicate. The silicate may be present in anyof its various forms. The purpose of a silicate is to offset thecorrosion tendencies of the phosphate ion in one of the compositions andalso to provide corrosion protection to aluminum heat rejectingsurfaces, including engine heads and radiators.

[0022] Both compositions must contain the indicated amounts ofmercaptobenzothiazole, tolyltriazole, and benzyltriazole. These azolesprotect copper and copper alloys from corrosion by forming an imperviousfilm with copper on the metal.

[0023] The borate containing composition must contain from 0.25 to 1.25weight percent of the borate, such as borax. The borate may be presentin any of its various forms. Borate is a good pH buffer. It is used tooffset the tendency of the pH of the composition to decrease when acidicexhaust gases from the engine get into the composition.

[0024] Any other composition, from 0.5 to 1.6 weight percent ofphosphate, such as sodium phosphate, must be present. It is important inthe protection of the metal surfaces from cavitation corrosion and alsoprovides corrosion protection to ferrous metal components.

[0025] It is desirable to include an effective amount of an antifoamingcomposition in the antifreeze/coolant composition. Such components arewell known. Polyglycol-type antifoaming agents can be used. In theborate composition, the amount of antifoam ranges from 0.05 to 0.3weight percent and in the phosphate composition, the antifoam maycomprise 0.05 to 0.10 weight percent of the composition. TABLE 3 OrganicAcid Chemical Percentage 1,3 Propanediol 97% to 98% by volume 93 to 95percent 2-Ethylhexanoic acid  4.0 to 6.0% Sebacic acid  0.0 to 1.5%Sodium Tolyltriazole 0.30 to 1.1% Antifoam 0.05 to 0.3% Dye 0.00 to0.02%

[0026] TABLE 4 Heavy Duty Organic Acid Chemical Percentage 1,3Propanediol 97% to 98% by volume 93 to 95 percent Sodium Nitrite 0.50 to1.50% 2-Ethylhexanoic acid  4.0 to 6.0% Sebacic acid  0.0 to 1.5% SodiumTolyltriazole 0.30 to 1.10% Sodium Molybdate 0.50 to 1.30% Antifoam 0.05to 0.10% Dye 0.00 to 0.02%

[0027] We have also found that organic acid inhibitor packages areeffective in the PDO antifreeze/coolant compositions. The Organic Acidtable below describes such a composition. The Heavy Duty Organic Acidtable below describes another antifreeze/coolant composition containingPDO.

[0028] The use of PDO also allows formulation of antifreeze/coolantswith environmentally friendly additives, perhaps eliminating the needfor nitrite which is unacceptable for use in Europe.

[0029] It is believed that PDO coolants in fuel cell vehicles would havean electrical resistivity of greater than 250 kOhm-cm, a boiling pointof greater than 90° C., a freezing point of less than −40° C., a thermalconductivity of greater than 0.4 W/m-k, a viscosity of less than 1 cPsat 80° C. and less than 6 cPs at 0° C., a heat capacity of greater than3 kJ/kg-K, a durability of greater than 5000 hours of operation (threeyears total time), material compatibility—will not corrode or erodecurrent automotive cooling system materials, have a toxicity classifiedas non-toxic for transportation, and will be cost competitive withcurrent automotive coolants.

[0030] The PDO formulations give intrinsically better protection againstcavitation than EG or PG.

[0031] It is our theory that some or all of these advantages are basedupon the relative chelation ability of PDO versus EO and PO. The latterare readily able to chelate the ions in the solution. The chelate withEO and PO will be a five-membered ring which is relatively easy to form.PDO cannot chelate the ions in solution very well because it has to forma six-membered ring and this is very hard to do.

EXAMPLES

[0032] In order to learn if the new chemistry offered benefits comparedto EG based engine coolants, three sets of ASTM D3306/D6210 style testprotocols were commissioned. These tests followed the ASTM protocol,except that the testing temperatures were increased to the maximum safeoperating temperature of each performance testing apparatus. Thisadaptation was designed to increase the severity of the test, tosimulate the increased thermal stress contributed by the EGR equippeddiesel engines, and to learn if the new chemistry would resist prematureaging better than EG. Each test pair included an EG and a1,3-propanediol fluid prepared per the appropriate ASTM standard testmethods. Each of the three pairs represented one inhibitor chemistry.

[0033] Automotive (light duty)

[0034] The first round of tests evaluated 1,3-propanediol inhibited withan inhibitor package described in the GM 6043 antifreezeformulation/specification. This inhibitor package, in EG, representedthe factory-fill for all North American GM cars until 1994. Itsproperties are well known and the chemistry offered a good opportunityto assess the probable performance of 1,3-propanediol by using ASTMlaboratory tests.

[0035] Inhibited with the GM 6043 chemistry, the 1,3-propanediolperformed somewhat better than EG in modified ASTM-type tests. FIG. 1illustrates the aqueous solution freeze point characteristics of the1,3-propanediol and GM 6043 (EG). There is a slight compromise of freezeprotection as determined by the ASTM D1177 test method, but the1,3-propanediol was soft and slushy at the reported freeze point. Thiscould be an indication that actual protection against hard, damagingfreezing is actually better, approaching the effective protection pointof the EG-based product. We also performed the D1177 test with 55% and60% 1,3-propanediol in water, and found that the 55% concentratedproduct offered protection equivalent to 50% EG, per the test method.Freeze protection continued to improve at 60% 1,3-propanediol. We feelthat the antifreeze properties of the chemistry are acceptable. Indeed a50% solution would provide adequate protection against freezing in mostgeographies.

[0036] The boiling point of the 50% solution by ASTM D1120 is 106° C.,one degree lower than the 50% EG at 107° C.

[0037] 1,3-propanediol has a slightly lower Specific Gravity (SG) thanEG when measured by the ASTM D1122 method. The EG based antifreeze wasfound to have a SG of 1.129 whereas the 1,3-propanediol SG was measuredat 1.070. Neither coolant had any effect when subjected to the Effect onAutomotive Finish evaluation (ASTM D1882). Indeed, as illustrated below,many of the physical properties of the two coolants are very similar.The similarity is beneficial, because the new coolant will almostcertainly be contaminated from time to time with EG and/or PG basedcoolants. When contamination occurs, it would be desirable that no harmto the system result. Presumably only some of the anti-oxidation benefitwould be lost.

[0038] The water content of the antifreeze is contributed by theinhibition technology, so there is no difference in the two basealternatives. Similarly, pH, chloride and ash characteristics wereequivalent. The foaming tendency of the 1,3-propanediol was slightlyhigher, but remained within the ASTM D3306 limits. (Tables 5, 6, and 7)TABLE 5 Physical Tests 1,3-propanediol GM 6043 Test Number & Description6043 (EG) D1122 Specific Gravity 1.070 1.129 D1177 Freeze Point −28° C.−38° C. 50% vol. in water (−18° F.) (−36° F.) D1120 Boiling Point 106°C. 107° C. 50% vol. in water (222° F.) (226° F.) D1882 Auto FinishEffect none none D1119 Ash Content 0.81% 0.87% D1287 pH: 50% vol. in DI9.8 8.67 water D3634 Chloride 16 11 D1123 Water, mass percent 4.1% 4.0%D1121 Reserve Alkalinity 98 9.3 D1881 Foaming Tendencies Break 3.6 SecBreak 1.6 Sec Vol. 113 ml Vol. 50 ml

[0039] TABLE 6 Glassware Tests Test Number & 1,3-propanediol GM 6043Description 6043 (EG) D4340 Corrosion of 0.27 mg/cm²/week 0.12mg/cm²/week Aluminum Heat Rejecting Surface D1384 Corrosion in Cu 3 mg 3mg Glassware Solder 1 mg 1 mg Brass 2 mg 2 mg Steel 1 mg 1 mg Cast Fe 2mg 1 mg Cast Al 0 mg 0 mg

[0040] TABLE 7 Performance Tests Test Number & 1,3-propanediol GM 6043Description 6043 (EG) D2570 Simulated Service Cu 3 mg 5 mg Solder 0 mg 4mg Brass 7 mg 0 mg Steel 1 mg 3 mg Cast Fe 0 mg 3 mg Cast Al 4 mg 1 mgD2809 Water Pump 8 8 Cavitation-Erosion

[0041] The data reported to this point were developed to learn if1,3-propanediol had potential as an engine coolant.

[0042] The data prove that the properties of the new chemistry arefavorable, and justified further research. The next stage of researchtargeted commercial fleet engines.

[0043] Fully Formulated (heavy duty)

[0044] The second round of tests evaluated 1,3-propanediol as aheavy-duty or ‘universal’ fleet-targeted coolant. This course of testingwas undertaken because of reports that EG-based coolants in heavy dutydiesel trucks equipped with prototype EGR devices were turning black andcorrosive in less than three months/50,000 km. To determine theviability of 1,3-propanediol as a heavy-duty coolant, it was preparedwith both the ASTM D6210 type ‘A’ and type ‘B’ inhibitor chemistries.These chemistries, in addition to the requirements that they meet theperformance specifications for cars and light trucks, are required tocontain chemistry to protect wet sleeve liners againstcavitation-erosion. The tests were run against an EG control. Thecoolant samples were all prepared in the laboratory, using the sameinhibitor provided by two major inhibitor manufacturers. TABLE 8 TYPE‘A’ Chemical Percentage 1,3 Propanediol 97-98% by volume 95 to 97percent Sodium Nitrite 0.50 to 1.5% Sodium Nitrate 0.30 to 1.5% Borax0.25 to 1.25% Sodium Mercaptobenzothiazole 0.25 to 1.0% SodiumTolyltriazole 0.30 to 1.1% Sodium Benzyltriazole 0.00 to 1.0% SodiumSilicate 0.25 to 3.0% Antifoam 0.05 to 0.3% Silicate stabilizer 0.10 to1.9% Dye 0.00 to 0.02%

[0045] TABLE 9 TYPE ‘B’ Chemical Percentage 1,3 Propanediol 97-98% byvolume 95 to 97 percent Sodium Nitrite 0.50 to 1.50% Sodium Nitrate 0.30to 1.50% Sodium Phosphate 0.50 to 1.60% Sodium Mercaptobenzothiazole0.25 to 1.00% Sodium Tolyltriazole 0.30 to 1.10% Sodium Benzyltriazole0.00 to 1.00% Sodium Silicate 0.25 to 3.00% Sodium Molybdate 0.50 to1.30% Antifoam 0.05 to 0.10% Dye 0.00 to 0.02%

[0046] 1,3-propanediol appears to offer intriguing advantages. The data,reported in Tables 10-12, reveal potential advantages in reducedoxidation (aging) and advantages in corrosion protection, especiallyprotection against lead solder bloom. These tests were run at highertemperatures, where possible, than is specified by ASTM D6210, so thedata should not necessarily be viewed as ‘pass’ or ‘fail’ per thestandard, but as research experiments.

[0047] In the elevated temperature aluminum heat rejection test, D4340,reported in Table 11, the coolants were operated for 168 hours at 150°C. The standard method specifies 168 hours at 135° C. Similarly, thetemperature was elevated in the D1384 and D 2570 to the maximumsustainable in the equipment. The operating temperature modificationsare noted in the data tables, below: TABLE 10 Physical Properties1,3-propanediol Control EG Test Number & Description 6210 ‘A’ 6210 ‘A’D1122 Specific Gravity 1.067 1.127 D1177 Freeze Point −30° C. −38° C.50% vol. in water (−21° F.) (−36° F.) D1120 Boiling Point 107° C. 107°C. 50% vol. in water (226° F.) (226° F.) D1882 Auto Finish Effect Noeffect No effect D1119 Ash Content 0.55% 0.80% D1287 pH: 50% vol. in DI11.25 11.0 water D3634 Chloride 24 25 D1123 Water, mass percent <3.0%<3.0% D1121 Reserve Alkalinity 6.8 8.8 D1881 Foaming Tendencies Break3.3 Sec Break 2.1 Sec Vol. 65 ml Vol. 55 ml

[0048] TABLE 11 Glassware Tests 1,3-propanediol Control EG Test Number &Description 6210 ‘A’ 6210 ‘A’ D4340 Corrosion of Aluminum 0.28 0.20 HeatRejecting Surface @ mg/cm²/week mg/cm²/week 150° C. pH Before & AfterTest 11.3 & 8.6 11.0 & 8.2 D1384 Corrosion in Cu 3 mg 4 mg Glassware @150° C. Solder 2 mg 26 mg  Brass 2 mg 2 mg Steel 1 mg 1 mg Cast Fe 0 mg0 mg Cast Al 4 mg 0 mg

[0049] TABLE 12 Performance Tests 1,3-propanediol Control EG Test Number& Description 6210 ‘A’ 6210 ‘A’ D2570 Simulated Cu 12 mg 8 mg Service @87° C. Solder 11 mg 56 mg  Brass  4 mg 1 mg Steel  3 mg 1 mg Cast Fe  0mg 1 mg Cast Al  0 mg 0 mg D2809 Water Pump 8 3 Cavitation-Erosion

[0050] The data are interesting in that, in this set of tests, two ofthe annoying tendencies of “type A” formulations are soundly dampened bythe 1,3-propanediol. Namely, the solder corrosion in D1384 and D2570 andthe water pump erosion sometimes seen in the D2809, as was reported inthis sequence. The coolant from the Simulated Service tests, whichrequires about ten weeks to complete, was analyzed after the test to seeif any resistance to oxidation could be documented.

[0051] This data suggested that high temperature characteristics of1,3-propanediol may be better, that it may resist degradation comparedto EG while offering equivalent to slightly better corrosion protectionevidenced by D1384 and D2570 data. In particular, chemical analyses ofthe coolants was conducted to quantify and compare the degradation ofcoolants as evidenced by the concentration of oxidation products. Ascoolant ages in use, some of the glycols oxidize. Ethylene Glycol mayform formic acid (CH₃—COOH) or either of two C₂ molecules: glycolic acid(HO—CH₂—COOH) or oxalic acid (HOOC—CH₂₋CH₂—COOH). 1,3-propanediol wasalso reviewed for larger carboxylates, in case degradation of thischemistry might produce them (FIG. 2).

[0052] 1, 3-propanediol inhibited with a “Fully Formulated Type ‘A’Inhibitor Package” produced very positive data. In the high temperaturetesting, data either were equivalent to or better than the EG.Significant improvements were documented in lead solder performance,aluminum water pump erosion/corrosion and degradation of the coolantchemical base*.

[0053] Corrosion in Glassware, the ASTM D 1384 method, was performedwith the standard set of six metal samples. The data for each the sixmetals are reported in table 11. The standard test requires 336 hours ofexposure at 88° C. This test was run for 336 hours at 150° C. by using apropylene glycol bath instead of water. Similarly, The coolanttemperature was elevated in the D4340 apparatus.

[0054] The maximum safe operating temperature of the simulated servicerig was deemed to be 93° C., five degrees warmer than the normaloperating temperature of 88° C. In general, the data from the simulatedservice paralleled that of the Corrosion in Glassware test.

[0055] Finally, the two coolants were evaluated in the Hot Surface Scaletest. There are currently no ASTM requirements or suggestions for limitsin scale formation resulting from this method. The method involvesintroducing a fluid consisting of 8 vol % of the sample mixed incorrosive hard water into the test apparatus. The apparatus is operatedfor 100 hours, exposing the sample to a hot steel surface in order tolearn if the chemistry can prevent the formation of scale. The control‘type A’ performed somewhat better than the new ‘type A’, but bothperformed well. The control generated 1.6 milligrams of scale and thenew chemistry 2.3 milligrams. Uninhibited ethylene glycol and hard watertypically accumulate about 5 milligrams. This data suggests bothchemistries would prevent serious scale formation in service, aprediction that has been confirmed by positive fleet experience with the‘type A’ formulation in an ethylene glycol based coolant.

[0056] The research next turned to repeating the testing using “FullyFormulated Type ‘B” Inhibitor”. The new chemistry surprised theresearchers by displaying unexpected reactions in the course of blendingthe ‘type B’ formulation-it solidified. Although a most intriguingevent, this behavior was not useful in the evaluation of the product asan engine coolant. Experimentation finally succeeded in a method thatrequired first blending the ‘type B’ inhibitors in water and lastlyadding the antifreeze chemistry to successfully produce the prototypeproduct. If marketed, this variation may only be available as a“ready-to-use” coolant. Of course, further formulation may find a way toovercome this most peculiar property.

[0057] They ‘type B’ chemistry differs from the ‘type A’ in that itincludes phosphate in place of borate and adds molybdate and anadditional anti-cavitation inhibitor for wet-sleeve lined dieselengines. The two types of heavy-duty coolants herein evaluated areapproximately equally represented in North American fleets. Type ‘B” maybe more a bit more common in the global marketplace. Chances are thatthe final formulations for both variations will be optimized for1,3-propanediol. Each of the two has produced interesting data, each hadadvantages and disadvantages over the other. TABLE 13 PhysicalProperties for Type ‘B’ 1,3-propanediol Control EG Test Number &Description 6210 ‘B’ 6210 ‘B’ D1122 Specific Gravity 1.062 1.135 D1177Freeze Point −30° C. −38° C. 50% vol. in water (−21° F.) (−36° F.) D1120Boiling Point 107° C. 108° C. 50% vol. in water (226° F.) (228° F.)D1882 Auto Finish Effect No effect No effect D1119 Ash Content 1.58%1.76% D1287 pH: 50% vol. in DI water 10.6 10.5 D3634 Chloride 10   10  D1123 Water, mass percent <3.0% <3.0% D1121 Reserve Alkalinity @ 50%11.4 10.8 D1881 Foaming Tendencies Break 4.2 Sec Break 2.2 Sec Vol. 215ml Vol. 85 ml

[0058] TABLE 14 Glassware Tests for Type ‘B’ 1,3-propanediol Control EGTest Number & Description 6210 ‘B’ 6210 ‘B’ D4340 Corrosion of Aluminum0.32 9.0 Heat Rejecting Surface @ mg/cm²/week mg/cm²/week 150° C. pHBefore & After Test 8.3 & 8.3 8.9 & 10.0 D1384 Corrosion in Cu 2 mg 1 mgGlassware @ 150° C. Solder 2 mg 2 mg Brass 1 mg 2 mg Steel 2 mg 5 mgCast Fe 0 mg 7 mg Cast Al 0 mg 0 mg

[0059] TABLE 15 Performance Tests for Type ‘B’ 1,3-propanediol ControlEG Test Number & Description 6210 ‘B’ 6210 ‘B’ D2570 Simulated Cu 3 mg 1mg Service @ 87° C. Solder 1 mg 58 mg  Brass 8 mg 1 mg Steel 2 mg 0 mgCast Fe 0 mg 0 mg Cast Al 1 mg 8 mg D2809 Water Pump 9 8Cavitation-Erosion

[0060] In 1,3-propanediol, an optimized chemistry offers an excellentperforming product that offers long service intervals and superiorcorrosion protection. The data for the Type ‘B” formulation follows intables 13, 14 and 15:

[0061] The hot scale test was also performed on the 1,3-propanediol type“B”. There was no scale formed on the hot surface (0.0 mg). The teststand was inspected, and the correctness of the test has been verified.The EG control experiment generated 1.75 mg of scale.

[0062] The data from the type ‘B’ experiments are similar to the datafrom the type ‘A’. There is evidence that the oxidation of the coolantis faster in EG than in 1,3-propanediol. This evidence is that theformates and glycolates are significantly lower in 1,3-propanediol thanin EG-based coolant. The same may be observed in the sulfate, usuallypresent as an oxidation product of mercaptobenzothiazole (MBT).Interestingly, the nitrite concentration was lower in both type ‘A’ andtype ‘B’ coolants in 1,3-propanediol.

[0063] A prospective new base chemical has been discovered that resistsoxidation due to thermal stress better than ethylene glycol. Thechemistry, 1,3-propanediol, may be successfully inhibited withconventional light duty and fully formulated engine coolant inhibitiontechnologies. The coolant base has passed all of the standard ASTM testsat increased temperatures, demonstrating its capabilities in severeoperation environments.

[0064] The chemistry described and claimed herein meets ASTM enginecoolant performance standards.

We claim:
 1. An anti freeze/coolant for internal combustion engineswhich comprises: 1,3 propanediol 97-98% by volume, 95 to 97 percent;nitrite, 0.50 to 1.5%; nitrate, 0.30 to 1.5%; borate, 0.25 to 1.25%;mercaptobenzothiazole, 0.25 to 1.0%; tolyltriazole, 0.30 to 1.1%;benzyltriazole, 0.00 to 1.0%; silicate, 0.25 to 3.0%; antifoam, 0.05 to0.3%; silicate stabilizer, 0.10 to 1.9%; and dye, 0.00 to 0.02%
 2. Ananti freeze/coolant for internal combustion engines which comprises: 1,3propanediol 97-98% by volume, 95 to 97 percent; nitrite, 0.50 to 1.50%;nitrate, 0.30 to 1.50%; phosphate, 0.50 to 1.60%; mercaptobenzothiazole,0.25 to 1.00%; tolyltriazole, 0.30 to 1.10%; benzyltriazole, 0.00 to1.00%; silicate, 0.25 to 3.00%; molybdate, 0.50 to 1.30%; antifoam, 0.05to 0.10%, and dye 0.00 to 0.02%.
 3. An anti freeze/coolant for internalcombustion engines which comprises: 1,3-propanediol is 93 to 95% byweight, 2-ethylhexanoic acid is 4.0 to 6.0%, sebacic acid is 0 to 1.5%,sodium tolyltriazole is 0.3 to 1.1%, antifoam is 0.05 to 0.3% and dye is0 to 0.02%.
 4. An anti freeze/coolant for internal combustion engineswhich comprises: 1,3-propanediol is 93 to 95% by weight, sodium nitriteis 0.5 to 1.5%, 2-ethylhexanoic acid is 4.0 to 6.0%, sebacic acid is 0to 1.5%, sodium tolyltriazole is 0.3 to 1.1%, antifoam is 0.05 to 0.3%and dye is 0 to 0.02%.
 5. An anti freeze/coolant for fuel cell vehicleswhich comprises 1,3-propanediol.
 6. A method for temperature protectionof fuel cells used in fuel cell vehicles which comprises using1,3-propane diol in the fuel cell as an antifreeze/coolant.
 7. A methodfor making an antifreeze/coolant composition for internal combustion andfuel cell engines comprising 1,3 propanediol 97-98% by volume, 95 to 97percent; nitrite, 0.50 to 1.50%; nitrate, 0.30 to 1.50%; phosphate, 0.50to 1.60%; mercaptobenzothiazole, 0.25 to 1.00%; tolyltriazole, 0.30 to1.10%; benzyltriazole, 0.00 to 1.00%; silicate, 0.25 to 3.00%;molybdate, 0.50 to 1.30%; antifoam, 0.05 to 0.10%, and dye 0.00 to0.02%, which comprises first blending the nitrite, nitrate, phosphate,mercaptobenzothiazol, tolyl triazole, benzyl triazole, silicate,molybdate, antifoam, and optional dye in water and then adding1,3-propane diol to the blend.